The historic city, listed by Forbes as one of the 15 lost cities of the world, has more than 50 Islamic monuments which have been found after removing the vegetation that had obscured them from view for many centuries. The site has been recognized as a UNESCO World Heritage Site in 1983 under criteria (iv), "as an outstanding example of an architectural ensemble which illustrates a significant stage in human history",[4] of which the Sixty Pillar Mosque (Shat Gombuj Masjid in Bengali), constructed with 60 pillars and 77 domes, is the most well known.[2][5] Apart from these monuments, UNESCO also includes the mausoleum of Khan Jahan, the mosques of Singar, Bibi Begni, Reza Khoda, Zindavir among the unique monuments.[4][6]

The mosque city is situated at the confluence of Ganges and Brahmaputra Rivers, at a maximum of around 60 kilometres (37 mi) from the sea coast. The city is spread over an area of 50 square kilometres (19 sq mi),[4] on the banks of the Moribund branch of the Bhairab River along a 6 kilometres (3.7 mi) stretch (in an east west direction and about 25 kilometres (16 mi) width in north-south direction[3]), which was part of the Sundarbans mangrove forests. According to numismatics, it was built in the 15th century and was known by the name of Khalifatabad during the 16th century. Given the nature of the heavy forest habitat and it being inhabited by tigers, the city was developed with unique infrastructure to make it inhabitable.[2][3][4][6][7] Today all monuments are set in the unspoilt environment of what is now farmlands, surrounded by palm trees.[1]

The history of the present-day Bagerhat is traced to the Bengal Sultanate under the rule of Sultan Nasir al-din Mahmud Shah (1442–1459[8]). It was established by the Ulug Khan Jahan (1433–1459), an administrator under the sultanate in the 15th century; an inscription on his tomb here mentions 1459 as his date of death, testifying the construction of the city in the mid 15th century. He was responsible for establishing a planned township with roads, bridges, and water supply tanks (ponds – two are still surviving: the Ghoradighi and Dargadighi), cisterns, and a very large number of mosques and tombs, and palaces and his own mausoleum, all attributed in the same “Khan Jahan Style”; Khan Jehan lived in the town and did extensive philanthropic work.[2][7] It is mentioned that the Delhi Sultanate, for political and religious reasons, wanted to establish an outpost of Islam in the then-remote part of India in Bengal and deputed Ulug Khan Jahan to brave this task.[2][9]

Ulug Khan was known for his unique capability as an administrator (administered the districts of Jhenaidah, Sathkira, Patuakhali, and Barisal in South Bengal) and a builder. He was also a pir, a saintly person who shunned personal aggrandizement (who rejected royal titles and did not issue any mint in his name). His tomb is thus venerated in Bangladesh and attracts a large number of pilgrims.[7]

A study of ten mosques and tombs seen in the town reveals that seven of them — Shait Gumbaz Mosque, which adjoins the Ulug Khan Tomb, Ranbijaypur Mosque, Bibi Begni Mosque, Shingra Mosque, Chunakhola Mosque, the Nine Domed Mosque are in Ulugh Khan style. The other three mosques of a later period are the Ten Domed Mosque, Rezai Khan Mosque and Zinda Pir Tomb.[3][7]

In 1895, an extensive survey of the area was conducted, and restoration was put into effect in 1903-04 on the Shait Gumbaz mosque. In 1907-8 part of the roof and 28 domes were restored.[10]

In 1982-83, UNESCO drew up a master plan for the Bagerhat area and it became a World Heritage Site in 1985.[11]

The planning of the city is distinctly dominated by Islamic architecture style; in particular, the embellishments are a combination of Mughal and Turkish architectural styles. The city covered 360 mosques[4] (most of them of identical designs), many public buildings, mausoleums, bridges, network of roads and water reservoirs. The material used in building construction was baked bricks, which over the centuries deteriorated under saline conditions of the soil and the atmosphere.[4][6]

The layout, revealed after the recent removal of the vegetative growth around the historic city, indicates that the city developed in two distinct zones; the main zone is the Mosque of Shait Gumbaz and its precincts and the other zone to its east is the one encircling the Mausoleum of Khan Jahan. The two zones are separated by a distance of 6.5 kilometres (4.0 mi).[4][6]

The minarets embellish the front corners of the mosques. They stand at double the height of the facade. The towers at the rear corners are also similarly fashioned. The minarets are double storied and round in shape; projecting cornices surround the shafts up to the middle height of the minarets and a window fitted at this mid height provides ventilation and light. A spiral staircase in this minar leads to the top. Artificial tusks of elephants decorate the exterior of the minarets.[12]

The Sixty Pillar Mosque (the Shat Gambuj), in Bagerhat in south Bangladesh, on the eastern bank of a sweet water tank or pond (the takur dighi) is one of the oldest mosques in the country and is described as "historic mosque representing the Golden Era of Muslim Bengal".[13] It is laid is over an area of 160 feet (49 m) by 108 feet (33 m).[1] The mosque is unique in that it has 60 pillars that support 77 exquisitely curved "low squat domes" that have worn away over time; it has seven central domes that are four-sided and built in Bengali style.[1] It was established in 1440 by Khan Jahan Ali.

It was used for prayers, as an assembly hall and madrasa (an Islamic school). Seventy seven domes are over the roof and four smaller ones at the four corners are towers (the towers were used to call the faithfuls to attend prayers). The large prayer hall has 11 arched doorways on the east and 7 each on the north and south which provide ventilation and light to the hall. There are 7 longitudinal aisles and 11 deep bays in the midst of slim columns made of stone. These columns support the curving arches that are overlaid by the domes.[2] The west wall in the interior has eleven mihrabs that are decorated with stonework and terracotta and the flooring is brickwork. The walls and the mihrabs were affected by sulphates. Most of the damage has been rectified. The arches are 6 feet (1.8 m) thick with a slight taper over the hollow and round walls. The mosque also functioned as the court of Khan Jahan Ali. It now attracts a large number of tourists and visitors. The mosque is decorated mostly with terracotta and bricks.[1][2][4][6][8][14]

The Nine Dome Mosque is located to the west of the takur dighi tank and built in the 15th century, it is close to Khan Jahan Ali's Tomb. Its western wall conventionally faces west towards Mecca, where the mihrab is inset on the western wall; terra cotta floral scrolls and flower motifs are the decorations seen around the mihrab. Circular towers are provided in the four corners. The walls of the mosque support a large central dome which has eight smaller domes around it. This structure was also affected by sulphates. It has been since substantially restored. Close to this mosque are the Zinda Pir Mosque and mazar (tomb), which are in ruins.[2]

The Singara Mosque is across the road from the Saith Gumbaz Mosque on its southeastern side. It has a single dome which is heavily built and a wide dome. In the typical style of the Khan Jahan Ali, the dome is supported on thick walls and topped with a cambered cornice. The Bigi Begni Mosque and the Chuna Khola Mosque are also of single dome type but much larger in size compared to the Singara Mosque. Last reported, the mosque was in a state of decay and renovation works were envisaged.[1][2]

The Ronvijoypur Mosque has the largest dome in Bangladesh.[2] It is of 11 metres (36 ft) width supported by arches and pendentives.[1] The corners have tapering circular turrets while the external cornice has a slight curve. The mosque's interior is plain. However the main mihrabs have decorations of floral patterns. It is located on the opposite side of the Khan Jehan Mausoleum, on the Khulna Bagerhat road. It is built according to Khan Jehan style of architecture. It has been renovated many times in the past during the 1960s and 70s. However, it needs further repair work to prevent dampness inside the tomb, and also to the brickwork on the exterior surfaces.[1][2]

The Chuna Khola Mosque, built in the 15th century, is located in the midst of rice fields in the village of Chuna Khola (named after the limestone extraction that was in vogue here in the past). It has been identified as representing a transition from the Khan Jehan style monuments. It is a 7.7 metres (25 ft) square building with 2.24 metres (7 ft 4 in) thick walls.[7] It has three entrances on the east and one each on the northern and southern sides also. It has three mihrabs with the central mihrab being the largest in size and projecting outwards. It has a hemispherical dome with frontal arches. There are also squinches and half domes. It is distinctly different from the Khan Jehan style mosque in its exterior decorations, particularly the east façade, which depicts four rectangular panels bordered by foliated scrolls with merlons having plant motifs. It has four turrets with curved cornices. The brick walls, in particular, were damaged due to sulphate effect. It was renovated in the 1980s according to guidelines set by UNESCO.[1]

The Six-Domed Mosque (also called the Rezakodha Masjid), built in the 15th century near thakur dighi pond, had six domes supported by stone columns. Protected under the Antiquities Act, the main mihrab displayed a chain and bell design. However, since it was all in ruins, a new building had been built, which has since been removed and the old ruins retained.[1]

The Khan Jahan Mausoleum or tomb is located on the northern bank of a water tank (a pond infested with crocodiles) called thakur dighi in Bengali language. The pond is square in shape and the excavated material from the tank was used to make an embankment over which the Mausoleum has been built. The pond is approached through a flight of broad and steep steps built from the embankment. It has a single domes structure built over a plan of 45 feet (14 m) square.[15] The building was made of brick walls over five layers of dressed stone which forms the basement. From recorded sources of 1866, it is also mentioned that the flooring had been inlaid with hexagonal encaustic tiles of different designs and colours (mostly blue, white and yellow). However, in its present condition such type of tiles are seen only on a few steps on the Mausoleum itself. The tomb has black stones have been used in making the tomb and it is made of three steps. Verses from the Koran are inscribed in Arabic and Persian. There are inscriptions on the walls of the crypt which are inferred as providing historical information about Ulugh Khan Jahan's life. After retirement, Khan Jehan spent his retired life here and after his death on 25 October 1459, his tomb was preserved here.[15] It is now pilgrimage site where people pay homage to the man who dedicated his life time to building the city and its monuments. The Pir Ali Tomb (of Pir Ali, a close associate of Khan Jahan) is an annex building to this mausoleum and is of identical layout. A mosque called the Dargha Mosque is attached to the mausoleum.[1][2][15]

A small museum has been established by the Directorate of Archaeology of Bangladesh, in collaboration with UNESCO, in front of the Shait Gumbaz Mosque, where antiquaries collected from the area of the historical site are displayed providing knowledge on the history of Bagerhat. It has three exhibit galleries of antiquaries related to the "Historic Mosque City of Bagerhat", which include inscriptions, potteries, terracotta plaques and ornamental bricks. Pictures of important historic buildings of Bangladesh are also part of the exhibits here.[16][17]